Hydrogenated block copolymers

ABSTRACT

HYDROGENATED BLOCK COPOLYMERS OF CONJUGATED DIENES AND MONOVINYL AROMATIC COMPOUNDS ARE DESCRIBED.

United States Patent @fice 3,598,886 Patented Aug. 10, 1971 3,598,886HYDROGENATED BLOCK COPOLYMERS Donald F. Hoeg, Mount Prospect, Eugene P.Goldberg, Highland Park, and John F. Pendleton, Park Ridge, 11].,assiguors to Borg-Warner Corporation, Chicago, 1]]. No Drawing. FiledSept. 15, 1965, Ser. No. 487,616 Int. Cl. C08f 15/04, 27/24 US. Cl.260-8791? 4 Claims ABSTRACT OF THE DISCLOSURE Hydrogenated blockcopolymers of conjugated dienes and monovinyl aromatic compounds aredescribed.

This invention relates to linear block copolymers and more particularlyto block copolymers of vinylcyclohexanes and olefins in which blocksequences of poly- (vinylcyclohexanes) are covalently bound to blocksequences of an alkyl-substituted polyethylene.

Homopolymers of vinylcyclohexane have been known in the art for manyyears, but have not demonstrated commercial value. These polymers havebeen characterized as clear, rigid, plastics having high heat distortiontemperatures but relatively poor impact strengths. Those efforts made toblend rubbery materials with the homopolymers of vinylcyclohexane toimprove their impact strength, did not meet with any measure of successand the resulting blends were cloudy, opaque materials with relativelypoor impact resistance. Perhaps the primary reason that the homopolymersof vinylcyclohexane were difficult to blend was due to theirincompatibility with rubber-like materials.

Vinylcyclohexane copolymers containing a majority ofpoly(vinylcyclohexane) structural units and lesser amounts of otherstructural units randomly interspersed in the main chain have also beenprepared. Two hydrogenated polystyrene copolymers of this type aredescribed in British Pats. 933,596 and 933,127 issued to Badische-Anilin and Soda Fabrik Aktiengesellschaft. These hydro genatedpolystyrene copolymers do not possess any marked improvements inphysical properties over the properties of thehomopoly(vinylcyclohexane). In fact, these copolymers generally lack acommercially valuable combination of physical and chemical properties.For example, the vinylcyclohexane-ethylene copolymer disclosed inBritish Pat. 933,596 (containing 10 percent ethylene) has asubstantially lower softening temperature than vinylcyclohexanehomopolymers. Similar polymers prepared by applicants herein have alsoshown very poor impact strength.

Several copolymers have also been described containing relatively smallamounts of vinylcyclohexane sequences derived from the partialhydrogenation of styrene-isoprene-styrene ternary block copolymers,e.g., South African Pat. 641,910. These materials are characterized bybeing rubbery, 10W tensile strength materials, however, they exhibitpoor aging characteristics. The residual unsaturation in these materialscontributes to the poor aging characteristics, specifically on exposureto actinic radiation. While not directed to vinylcyclohexane copolymers,British Pat. 863,256 discloses the partial hydrogenation of onestyrene-butadiene copolymer (containing 30 percent by weight styrene);this copolymer is alleged to have good tensile strength and lowtemperature flexibility. This copolymer does not, however, possessproperties as favorable as those of the vinylcyclohexane copolymers andin particular shows poorer aging characteristics as well asincompatibility with homopolymer (vinylcyclohexane).

The present invention is directed to vinylcyclohexanealkylsubstitutedpolyethylene block polymers wherein the polymers contain from about 8 toabout 82 mole percent vinylcyclohexane block structural units andcorrespondingly between about 92 and about 18 mole percentalkylsubstituted polyethylene block structural units.

An essential feature of the copolymers of this invention is that theycontain in excess of 18 mole percent of the alkyl-substitutedpolyethylene segments. Copolymers containing less than 18 mole percentare of limited commercial value and exhibit grossly inferior properties.Those block copolymers containing 18 mole percent and higheralkyl-substituted polyethylene sequences have an extraordinarycombination of physical and chemical properties ranging from tough,rigid, high heat distortion thermoplastics to strong thermoplasticelastomers depending, or course, upon composition.

The vinylcyclohexane-alkyl polyethylene block copolymers of thisinvention contain vinylcyclohexane structural units in linear polymerblock sequences of the formula:

R ltioa Li, I

F O RMULA. I

om-onz en ii L .LL ital.

FORMULA II wherein R may be hydrogen or a methyl group and R is ahydrogen, methyl, ethyl, or isopropyl group, and y and z are wholenumbers between 1 and 25,000 in the ratio y/x between 25/ 1 and l/ suchthat y+z25,000. In the block copolymers of this invention, at least oneof x and (y-l-z) are equal to or greater than 25.

In a preferred embodiment of this invention, in Formula I above, R is acyclohexyl group and R is hydrogen, and in Formula II above, R ishydrogen and R is a pendant ethyl group or a pendant methyl group.

Those copolymers containing in excess of about 50 mole percent ofpoly(vinylcyclohexane) block sequences are rigid, optically clearplastics of high heat distortion temperature and high tensile strengthwith good environmental stability and excellent impact strength. Therigid materials are very tough copolymers that are useful for makinginjection molded parts, extruded film, pipe, fibers and the like.

Those copolymers containing more than about 50 mole percentalkyl-substituted polyethylene sequences tend to be flexible andrubbery. In particular, those containing above about 65 mole percent arerubbery copolymers having good tensile strength, extensibility, and heatshrinkability as Well as exceptional aging stability and low temperatureflexibility. The flexible products are useful in applications such aswire coatings, packaging materials, films, fibers, extruded and moldedproducts, etc. The flexible products are also unique in that they areexcellent blending agents and are compatible with homopoly-(vinylcyclohexane) or copolymers containing poly(vinylcyclohexane). Whenthese products are blended with poly(vinylcyclohexane) polymers, theresulting blends have excellent properties including especiallyoutstanding impact strengths.

The copolymers of the present invention are conveniently prepared by theessentially complete hydrogenation of vinyl-substituted aromatichydrocarbon-conjugated diene block copolymers. In order to obtain theunique overall properties of the compositions of this invention, it isessential that the vinyl-cyclohexane block copolymers contain onlyminimal amounts of residual unsaturation after hydrogenation, generallyless than 3 percent aromatic unsaturation. As herein defined, therefore,complete hydrogenation is hydrogenation to the point where less thanabout 3 percent aromatic unsaturation remains. Since hydrogenation ofthe aromatic unsaturation is more difiicult than the aliphaticunsaturation, the degree of hydrogenation of aromatic unsaturation inthis invention insures essentially complete hydrogenation of thealiphatic unsaturation.

The preferred unsaturated block copolymer substrates utilized inpreparing the copolymers of this invention include linear, soluble,gel-free, block copolymers of vinyl aromatic monomers such as styrene,ot-methylstyrene, a,o-dimethylstyrene, vinyltoluene,a,m-dimethylstyrene, a,p-dimethylstyrene, vinylanisole,vinylnaphthalene, vinyl biphenyl, o-chlorostyrene, m-chlorostyrene,p-chlorostyrene, o, m, or p-fiuorostyrene, and vinylpyridine combinedwith a conjugated diene such as butadiene, isoprene, chloroprene,dimethylbutadiene, 1,3-pentadiene or the like. Unsaturated blockcopolymer substrates of mixtures of the aforementioned monomers may alsobe utilized.

The unsaturated block copolymer substrates utilized in this inventionmay be prepared by a variety of methods such as by using alkali metalsor organolithium compounds as polymerization initiatorsto causeformation of block sequences in a hydrocarbon solution. It will be notedthat a variety of different block structures may be obtained by varyingthe monomer addition sequences, rate of addition, temperature andsolvent. For example, it is known that addition of an alkyllithiumcompound, such as n-butyllithium, to a mixture'of butadiene-styrene in ahydrocarbon solvent produces a block copolymer consistingof a block ofpredominantly pure polystyrene sequences linked to a block of more orless mixed styrenebutadiene sequences. Polymers prepared in this manner,i.e., when both monomers are present initially, are hereinreferred to asmixed-block copolymers.

In the absence of reactive compounds such as water, carbondioxide,oxygen, proton sources in general, and the like, the polymerizationsinitiated by organolithium compounds in hydrocarbon solutions will beessentially free of chain termination or transfer events so that amultitude of block copolymer structures may be obtained by sequentialaddition of monomers. Subsequent to the complete polymerization of onemonomer, a second monomer may be added to produce a new polymeric blocksequence linked to the previously formed polymeric sequence to provide ablock copolymer of the type .AB, where A and B are distinct polymerblock segments. Block sequence length may also be controlled since thechain length depends only upon the amount of polymerizable monomerpresent and the number of active polymer chain ends. By alternating thesequence as Well as monomer type, the block structure, i.e., length anddistribut ion, can be controlled and block polymers derived from aplurality of monomers may be prepared.

Those polymers prepared by sequential addition of monomers will bereferred to herein as pure block structures. Mixed block copolymers ofstyrene and butadiene Will be referred to herein as SB binarystyrene-butadiene pure block copolymers as SB, ternarystyrene-butadiene-styrene pure block copolymers as SBS, ternarybutadiene-styrene-butadiene as BSB and styrene-isoprene polymers as SISI, SIS, ISI, SISIS, etc. as the case may be. When difunctionalinitiators, such as dilithiopentane are utilized in preparing the blockcopolymers of this invention, it is possible to make ternary blockcopolymers, as for example from styrene-butadiene, wherein the terminalportions are block homopolymers (homopolystyrene) and the centralportions are of mixed block structure. Pure block structures may also beprepared using difunctional initiators via the sequential addition ofmonomers as mentioned with respect to the pure block structures preparedwith monofunctional initiators.

Inasmuch as the solvent and other factors will exert an influence uponthe microstructure of the polydiene segments, control of the geometricisometry of the diene block sequences in the block polymer substrates isalso possible. The microstructure of the substrates is important becauseit will influence the properties of the resulting fully hydrogenatedpoly(vinylcyclohexane) block copoly mers. For example, block sequencesderived from butadiene polymerized l,4 yield, upon hydrogenation,unsubstituted polyethylene sequences. Those sequences which enter thepolymeric block via 1,2 polymerization yield ethyl-substitutedpolyethylene sequences upon hydrogenation. The block sequences of1,4-poly(isoprene) result in methyl-substituted polyethylene sequencesin amounts corresponding to one methyl-substituted methylene group forevery three methylene sequences. Block sequences containingpoly(isoprene) segments derived from 1,2 isoprene polymerization resultin a methyl and ethyl substituent on the same carbon atom of thepolyethylene chain.

As complete stereospecificity in the polymerization of the diene israrely obtained, a mixture of microstructures may be observed in thepolydiene block sequences of the substrates utilized in preparing theblock copolymers of this invention. For example, in the substratesderived from the block polymerization of styrene and butadiene, with anorganolithium reagent, the microstructure of the polybutadiene segmentsmay consist of about to about percent, 1,4- structure and about 5 to 10percent of the diene will enter the chain via the 1,2 addition toprovide pendant vinyl groups randomly distributed among the polydienesegments. When there is essentially complete hydrogenation, theresulting block copolymers contain approximately one ethyl group forabout every 15 methylene groups in the polyethylene. The presence of oneethyl group per 10 to 20 methylene units is sufficient to limit thecrystallization of the polyethylene. block segments in the unextendedstate and also contributes to the high optical clarity of thevinylcyclohexane-ethyl-substituted polyethylene block copolymers.

The presence of crystallizable polyethylene segments, and a limitedamount of crystallization of these segments upon deformation contributesto the exceptional strength properties of these copolymers. The highestrigidity and tensile strength are usually obtained in thosepoly(vinylcyclohexane)-alkyl-substituted polyethylene block copolymersin which the lowest alkyl content of the polyethylene sequence occurs.Those vinylcyclohexane-alkyl polyethylene block copolymers possessingthe highest tensile strengths and rigidity are also usually thosewherein the polybutadiene portions of the styrene-butadiene blockcopolymer substrates, from which these copolymers are prepared, containthe maximum 1,4 content (less than about l0 percent vinyl content).

In given applications, it may be desirable to decrease the rigidity anddensity of the copolymers. This may be accomplished by increasing theamount of alkyl group substitutions along the polyethylene blocksequence. When small amounts of aliphatic or cycloaliphatic ethers areused in the preparation of the vinylaromatic-diene block copolymersubstrates, the amount of 1,2 polymerization of the diene is increased,which in turn, results in a higher concentration of pendant vinylgroups. Hydrogenation of these substrates leads to a proportionatelyincreased alkyl group concentration along the polyethylene blocksequences.

The hydrogenation of the vinyl aromatic hydrocarbondiene block copolymersubstrate to prepare the copolymers of this invention may be carried outby a variety of methods. The hydrogenation may be accomplished byplacing the block copolymer substrate in a hydrocarbon solution in thepresence of a suitable catalyst and applying hydrogen gas under pressureto this solution. The method may be either continuous or a batchprocess.

The substrate polymer concentration may vary between about 0.5 percentto about 30 percent by weight of the hydrocarbon solution and ispreferably within a range of about 2 percent to about 20 percent.

Catalysts such as finely divided, supported and unsupported nickel, forexample, nickel-on-kieselguhr, have been found to be very effective. Thequantity of catalyst may be varied within a range of from about 0.1 toabout 400 percent by weight of the polymer used. In commercialapplications, it is desirable to keep down the residence time of thehydrogenation which may be achieved by high catalyst to polymer ratios.When the catalyst is used in high concentrations with respect to thepolymer, it must, of course, be separable from the fully hydrogenatedprodnot for re-use as a catalyst.

Under certain reaction conditions, for example, above 225 C., it may bedesirable to reduce the time in which the catalyst and polymer are incontact, which will also require a high catalyst/ polymer ratio.

The hydrogen pressure utilized in hydrogenating the substrate isgenerally in the range of about 100 p.s.i. to about 5,000 p.s.i. andpreferably within a range of between about 250 and 3,000 p.s.i.

The temperature of the reaction may range from about 100 C. up to thedegradation temperature of the specific polymer substrate beinghydrogenated. The temperature range is preferably between about 100 C.and about 350 C.

The reaction time under which the substrate is hydrogenated depends uponthe conditions of the reaction and may vary between a few minutes andabout 20 hours.

A As mentioned, it is important that the hydrogenation reaction becarried out until there is less than 3 percent residual aromaticunsaturation. One of the benefits of carrying the reaction to a minimumof 97 percent complete hydrogenation in addition to the unique polymerproperties so obtained, is that the catalyst may be more readilyseparated from the fully hydrogenated product by a number of techniquessuch as filtration, decantation, centrifugation, etc. Magnetic fieldsmay be applied to further improve catalyst separation.

The following examples illustrate a great variety of vinylcyclohexanealkyl substituted ethylene block copolymers, both mixed and pure blocks,prepared in accordance with this invention. The examples areillustrative of the invention and are not meant to limit the inventionin any way.

EXAMPLE 1 The following procedure was used in the preparation of thestyrene-butadiene mixed block copolymer substrates utilized in thisinvention.

28 oz. polymerization bottles, equipped with Teflon coated magneticstirring bars, were thoroughly dried in a forced air oven at 130 C. andcooled to room temperature under an argon purge. The bottles werecapped, upon cooling under an argon purge, with a metal perforated crowncap. The crown cap was equipped with a neoprene imperforate liner. 550ml. of cyclohexane was pressured into the polymerization bottle and wasdegassed by blowing argon through the rapidly stirred solvent.

A preselected amount of purified and distilled styrene was added via asyringe and argon purging was continued for a few minutes. The mixturewas cooled to approximately 10 C. and while stirring a purging solution,prepared from benzene, ot-methylstyrene, and n-butyllithium in hexane,was added until a permanent color change was detected. A preselectedamount of purified and distilled butadiene was added to thepolymerization bottle. A catalyst solution prepared from 25 ml. of 1.5 Nn butyllithium and 250 ml. of cyclohexane was added to the solution ofstyrene-butadiene. The amount of catalyst was determined by selectingthe molecular weight required and utilizing the formula:

Grams M oofmerno The polymerization bottle was placed in a water bath atC. and stirred magnetically for from about 5 to about 18 hours. Thereaction was terminated by adding a couple of milliters oftetrahydrofuran containing N- phenyl- -naphthylamine and methanol. Thepolymerizations listed hereinbelow were carried out at a solids contentof approximately 11 percent by weight.

The mixed block copolymers of styrene and butadiene listed in Table Iwere used as substrates to prepare the vinyl-cyclohexane mixed blockcopolymers of this invention. Under the column entitled Designation, thetype of copolymer is set forth as well as the weight percent of styrenein the copolymer. For example, in Run Number 1, 10 SB designates acopolymer containing 10 percent by weight styrene and also designatesthat it is of a mixed block type.

TABLE I n-Butyl- 1; s ./c D os1gna- Styrene Butadiene hthium, e.=0. 1 gRun No. tion Wt., g. Wt., g. mM: d1./g

EXAMPLE 2 The preparation of pure block polymers of styrene andbutadiene was carried out in the following manner. 550

ml. of cyclohexane was added to a 28 oz. polymerization bottle as inExample 1. ]Pure styrene monomer was added to the cyclohexane solution,and the impurities were titrated with purging solution as in Example 1.The required amount of n-butyllithium in cyclohexane was added toproduce the desired block length of polystyrene as calculated by theequation used in Example 1.

The polymerization bottle was placed in a 50 C. water bath and stirredvia a magnetic stirring motor for three hours. The 'bottle was removedand cooled to approximately 23 C., Weighed and pure butadiene wasdistilled into the polymerization bottle. After the desired weight ofbutadiene had been introduced, the bottle was again placed in the bath,and the polymerization was allowed to proceed until the butadiene waspolymerized (approximately five hours). The reaction was terminated asin Example 1. In this manner, a pure polystyrene block is connected to apure polybutadiene block. Pure SB block polymers prepared in this mannerare shown in Table II.

In Table II, SBS denotes pure block polymers containing a centralpolybutadiene block linked to two terminal polystyrene blocks and BSBdenotes pure block polymers containing a central polystyrene blockconnected to two terminal blocks of polybutadiene. These polymers wereprepared by a continuation of the procedure set forth for SB blocks.After completion of the polymerization of the second monomer, thedesired amount of new monomer was added. For example, in the preparationof the SBS polymers, the first styrene block was allowed to polymerizethree hours at 50 and the butadiene block was allowed to polymerize forfive hours at 50. The last block, Le, a polystyrene, was prepared in thesame manner as the first polystyrene block. i.e., the purged monomersolution was added by a syringe directly into the polymerization bottleat 50, and allowed to polymerize for three hours. This sequentialaddition was continued for the preparation of extended block copolymerssuch as SBSBS, which signified a polymer of alternating block TABLEII.-Contin ue(1 Butan-Butyln sp./c., lDusig- Styrene diene lithium,c.=0.1 g., Run No. nation wt., g. wt., g. mM. dl./g.

Block 1st 2nd 59 158138 8. 8 3. 8 43. 2 0. 39 1. 59 60 SBS 4. 5 4. 6 52.2 0.94 0. 85 61 158138 4. 7 4. 7 52. 2 O. 94 0. 88 62 LEOSBS 5. 5 5. 544. 1 0. 42 1. 45 63 SBS 7. 1 7.2 42.9 0.43 1.32 64 25SBS 6. 8 6. 7 40.3 1. 19 0. 68 65 58138 6. 7 6. 7 40.6 1. 19 66 95SBS 7. 5 7. 5 45.0 1.13 0. 79 67 258138 7. 5 7. 5 45.0 1.13 58 25SBS 7. 5 7.5 45. 0 0.92 0.8169 258138 7.5 7.5 45.0 1.0 0.87 70 25SBS 7. 5 7. 5 45.0 1. 0 0.83 12.012.0 41. 7 0.61 0. 92 18.9 18.2 15. 5 0. 18 1. 33 18. 1 19. 3 15. 1 0.17 1. 60 18. 7 19. 0 15. 0 0. 17 1. 60 18. 1 16. 8 15. 3 0. 22 1. 3O 18.1 16. 8 15. 1 0.22 1. 18. 1 18.0 17. 0 0. 33 1. 00 22. 9 20. 2 10. 9 0.33 1. 08 22. 9 20. 3 12. 1 0. 33 l. 03 22. 9 19.6 11.8 0.33 1.01 22. 620. 2 12. 5 0. 20 1. 20 22. 2 20. 7 7. 6 0. 17 1. 00 21. 4 20. 7 7. 9 0.17 1. 10 24. 6 24. 2 5. 7 0. 21 1. 34 24. 3 23. 8 5.8 0.21 1. 32 24. 524. 6 5. 5 0. 23 1. 25 24. 6 25. 1 5. 4 0.23 1. 17 41.0 5. 1 *5. 2 0.340. 98

*Butadiene added first and upon completion, styrene followed by anotherbutadiene block.

EXAMPLE III The preparation of pure block copolymers of styrene andisoprene was carried out in the manner described in Example 2,substituting isoprene for butadiene. The isoprene was purified anddistilled before use. The polymers prepared are shown in Table III.

TABLE III structure. Polymers prepared in this manner are shown Styrenem Table II wt., g. 150- 'nButy1- 1 sp./e., Desigprene lithium e =0.1g.,Run No. nation 1st 2nd wt.,g. mM. dL/g.

39 ussIs 0.2 0.3 3.85 0.31 1.06 TABLE II 25818 6.3 7.0 40.6 0. 49 1.007. 2 7 0.2 40.1 0. 49 1.03 3.2 0.44 0. 05 Butan-Butylna ion w g. w g. m

5 1 10-37 EXAMPLE 4 15513 4&2 The microstructure of the ol diene ortionsof the 158B 7.. 41.3 p y P 7.2 3 polybutadiene-polystyrene pure blockpolymer chalns was easily altered by the addition of tetrahydrofuran tothe 20813 11.5 46.0 gggg g? cyclohexane solvent. Relatively smallamounts of tetrahydrofuran and similar com ounds not onl th 25s}; 14.041.5 p y Increase e 25813 12.3 33.2 1,2 addition polymerization(increase vinyl content) of 13:3 33 the butadiene. but also tend torandomize the structure. 252% r 15.5 The procedure of having bothmonomers present initial- 8 2:; g: 4 I 1y, which produces mixed blockstructures in pure cyclogggg g 13% 0,17 l 24 hexane led to a morerandomlzed structure if tetrahydrofuran were present Conse uentl thetechn' f 309.13 45.0 11.7 0.22 0.75 5 lque 0 58 80813 45.8 12.1 0.220.75 0 quential monomer addition (pure block formation) was r 332% gig2:2 29 B: used 1n preparmg block polymers containing a hlgh Vinyl 90533.0 0.27 0.7 content. Using procedures as described in Example 2, 383g1B: 8; styrene-butadiene pure block polymers containing high vlnyl groupcontent were prepared as shown in Table IV.

TABLE 1v Buta- 71-Buty1- spJc. b St rene d li .Run No. DesignationSolvent 31 wtj' g 1 3 1 0 0 1.75.

258B (high 1,2) 500 m1. cyclohexane 25 m1. THE 1 13. 8 41. 9 0 46 0svosu 71,2) 001111. cyclohexanc 1 m1. T111"... 1 18.1 15.0 0118 ii:

The microstructure of the polydiene portions of poIymers prepared inthis and other examples was examined using infrared spectral techniquesand some of these results are shown in Table V.

in a heated pressure filter. The product (98.5) g. was isolated byprecipitation in methanol from the clear, hot solution and dried at 70C. in a vacuum drying oven. The specific viscosity in decalin at 135 was0.91 dl./ g. The other block copolymers were hydrogenated in a similarTABLE V manner. The degree of hydrogenation of the block suba ggfig ggstrate polymers was determined by infrared analysis of block, percent bythin films of the resulting polymers. The polymers pre- Polymerfmm weiht oipoly pared by the hydrogenation procedure outlined for the runDesignation Vinyl Trans 10 styrene block copolymers showed the completedisappear- 258B 43 L8 ance of absorption bands characteristic ofaliphatic un- 753B 1.7 15.2 saturation and little or no residual phenylbands 1% 08B (1mg The frequency used to measure styrene content was the690 cm:- band, which had been calibrated for precise styrene residuedeterminations. EXA 5 Some of the physical properties of the variousvinylcy- The preparation of the vinylcyclohexane-alkylpolyethclohexane-alkyl-substituted polyethylene block polymers yleneblock copolymers consisted of the essentially comare shown in Table VIIand VIII. Some of the physical plete hydrogenation of thestyrene-butadiene block coproperties of the styrene-dlene blockcopolymer substrates polymers. These hydrogenations were carried out incycloare shown 111 Table 111 the fables, under tensile P P hexane with anickel-on-kieselguhr catalyst in a one gallon erties, the followingabbreviations were used: T=Temstirred autoclave. A typical hydrogenationwas conducted perature, Y=Tensile Stress at Yield, U=Ultimate Tensile asfollows. Strength, and E=Elongation. HDT is the heat distortion 100 g.of a nickel-on-kieselguhr catalyst was slurried in temperature asmeasured in a modified ASTM Test 1250 mls. of cyclohexane and placed inan argon-filled #64856, modified in that the specimen dimensions wereautoclave. 100 g. of a 25 SBS polymer, having a specific x A" by /2"long and pressure was applied at the viscosity of 0.79 in benzene wasdissolved in cyclohexane center of the A" x /2" surface parallel to the/8" x A" to a volume of 1250 mls. and placed in the autoclave. The face.IS is the impact strength generally as measured by system was pressuredto 1930 p.s.i.g. with hydrogen at e the notched Izod Method indimensions of ft.lbs. per inch 32 and while stirring was heated to 175C. The resulting of notch; figures with a D following were measuredusing pressure was 2500 p.s.i.g. After three hours and 26 minthe Dynstatimpact strength technique and dimensions are utes, the uptake ofhydrogen had ceased and the pressure in kg.cm./cm. Flex. Mod. 15 thefiexural modulus of the remained constant at 1900 p.s.i.g. for two hoursand material. i I fifty minutes. The autoclave was cooled to roomtempera- The desi 0f the y y e ne-alky1substiture, vented, flushed withargon and the charge blown tuted polyethylene block polymers consist ofthe descripthrough a heated Ultipore filter. A one liter rinse followedtion of the unsaturated block copolymers from which they and thecombined solution was passed through Filteraid were prepared followed bythe letter R.

TABLE VI Tensile properties Polymer Flexural from run Designa- Temp., Y,U E, DT, modulus, number tion C. p.s.i. p.s.i. percent 0. LS. p.s 1Density 110 5 7 25SBM 100 5 "i366 14 sB 1,150 48 7 1. 02

88 SOBSB 90-91 25SIS 92-94 75SIS TABLE VII Preparation and properties ofthe viuylcyclohexanealkyl polyethylene block polymers Prepared Vinyleyclofrom 1 sp. /c. Tensile Flex.

hexane block substrate Decalm, D'I, I.S., mod.,

polymer Run No. Designation C. '1, C. Y, p.s.l. U, p.s.l. E, p.s.r. C.ft. lb. pm

97 1 IOSB R 1. 72 50 970 2, 480 630 98 2 15SB R 1.04 50 1,090 3,050 540TA BLE VII.Cn tinned Prepared Vinyl cyclofrom 1; spin. Tensile Flex.hexane block substrate ecalin, 1 7 HDT, I.S., mod., polymer Run No.Designation 135C T, O. Y, [1.5.1. U, 13.5.1. E,p.s.i C. 1t. lb. 13.5.1.

f :15 1,300 3, 200 000 99 3,4 15SB R 1.27 60 810 2 50 030 100 5,6 2051311 101 7 sB R 102 3,0 25SBMR 103 sB R 105 12 56sB R 106 13 TOSBMR 10%16,17 SB R .47

1s 70SB R .05 .1 110 19 74sB R 1. 32% 111 20,21 SOSB R 1.13% 112 22, 23sosB R 1. 02% 1 113 24-25-26 85SBMR 0. 70% 114 27,23 85SB R 0.01% 115 2000SB R 0.72% 116 30 QOSBMR 0.30% 117 31,32 00sB R 1.02%

113 33 05SB R 0.7 119 34 588R 2.84

120 35 10SBR 0.55% 121 36 15SBR 1.04% 122 37 ISSBR 1.07%

123 33, 30 16SBR 1.01

124 40 20SBR 1. 72% 125 41 BOSBR 1.35

1 15 1100 1540 550 :15 1,820 3,420 1100 12s 44-45 10 25SBR 1. 25 1101,340 2,500 1100 1 15 530 1,360 370 129 47 25SBR 05 1,600 1,000 50% 13048,40 70SBR 0.86% 131 50 75sBR 11.44% 132 51 BOSBR 1. 05% I: 133 52,53sosBR 0. 67 134 54 85SBR 0.64

136 55,56 QOSBR 0.73

TABLE VIL-Continued Prepared Vinyl cycle from 1; sp./c. Tensile Flex.hexane block substrate calin, HDT, I.S., nd., polymer Run No.Designation 135 C. '1, C. Y, p.s.i. U, p.s.i. E, p.s.i C. ft. lb.11.5.1.

3,360 5 136 57,58 QOSBR 0.81 3,990 5 135 0.2 390,000

2,400 500 137 59 IBBBSR 2.02 1,480 400 1,560 I 700 3,190 850 138 60,61SBSR 1.17 2,290 780 1,390 800 3,450 690 139 62 2OSBSR 1.83 3,100 5902,070 740 3,030 350 140 63 SBSR 1. 62{ 2,960 450 2,420 450 2,710 600 14164,65 25SBSR 0.93{ 1,940 500 a, so 820 142 66, 7 25SBSR 0. 01 v 75 2,600

2,800 440 143 68 25SBSR 0.96 2,280 500 7 4,500 540 145 71 SBSR 1.104,000 720 50,000

. 1, 500 680 4,230 5 146 72 SBSR 3,940 8 132 0.9 250,000 2,470 100 4,3007 147 73 70SBSR 1.52 3,750 5 132 1.0 290,000

. 2,870 9 r 4, 690 6 148 74,75 70SBS 1.29 3,920 6 138 1.1 280,000

3,070 28 5,180 7 150 78-79-80 SBS 0.88 50 4,230 7 137 0,6 410,000 v a,360 0 305, 000

. 4,880 5 151 81 SOSBSR" 1.02 4,190 5 144 0.5 330,000

3,470 5 3,500 5 152 82 SBSR 0.65 2,790 5 116 0.3 350,000

2,700 5 I 4,400 8 153 83 85SBSR 1.18 ,530 5 135 0.6 230,000

1 2, 540 5 4,110 5 154, 84,85 QOSBSR 0.99 5,240 5 126 0.3 370,000

I 3,120 5 5,380 5 155 86,87 QOSBSR 1. 02 5,200 6 136 0.6

- 75 4,000 e 156 88 SOSBSR 0.83 Toobnttle tomold v 13.5 0.2

I 240 1, 000 157 89 25SISR 1.39 870 1,000 590 1,200 I 1,120 960 15890,91 25SISR 1.37 820 1,000

V V V 1, 320 5 i 86 1,140 160 253B (1,2)R 0.89

. I 25 3,480 3,190 9 161 96 708B (1,2)SR 1.31 50 2, 790 2,520 10 140 1 3200,000

As mentioned, it is arr-essential aspect of this invention that theoverall balance of favorable properties of the vinylcyclohexane blockpolymers is achieved only by essentially complete hydrogenation of thevinylaromaticdiene block polymers. It is preferred that less than threepercent total residual unsaturation remain in the polymer. Thedeleterious influence of small amounts of residual unsaturation onproperties is clearly shown in the weatherometer test data shown inTable VIII.

TABLE VIIL-WEATHEROMETER AGING PROPERTIES 7 Hours Tensile propertiesexposure Polymer 'Prepared from weather- No. substrate number Degree ofhydrogenation ometer Y, p.s.i. U, p.s.l. percent Remarks 1 25683138 fromBun 99% 0 2,040 3,040 350 Tough and flexible. 'i4o' an 280 2, 200 2, 000sun ttfigh and 1 162... do Ca. 95%, 5%, residual 0 1, S40 2, 740 330Tough and flexible.

styrene unsaturation. 162 -(ln 280 1, 260 5 Completely embrittled.

Table VIIL-Continued IHours Tensile properties exposure Polymer Preparedfrom weather IE, 4 No. substrate number Degree of hydrogenation ometerY, psi. U, p.s.i. percent Remarks 145 7081315 from Run 99% 4, 530 t, 230hilexiible, 0.9 notched 1.0 145 ..do.- 165 8,360 5 Still flexible. 163do Ca. 90%, residual styrene 0 4.280 5 Flexible, 0.8 notchedunsaturation. izod. 163 ..do 165 B, 110 5 Completely embrittled.

It will be noted from the examples that thevinylcyclohexane-alkyl-substituted polyethylene block copolymerscontaining from about 8 to about 50 mole percent of a vinylcyclohexanestructural unit in polymeric block sequence are flexible, clear,thermoplastic materials of excellent tensile strength andextensibility,

Those block copolymers of this invention containingfrom about 8 toabout50 mole percent vinylcyclohexane structural units in polymeric blocksequences have significantly higher tensile strengths than thestyrene-diene block copolymer substrates from which they are pre--pared. This is especially true where the polydiene sub- 1 stratesequences are predominantly of the 1,4 type. For

example, the styrene-butadiene block polymer substrate prepared in Run 7of Example 1 was a very poor molding product which crumbled easily. Incontrast, the vinylcyclohexane block copolymer prepared by theessentially complete hydrogenation of this substrate possessed anultimate tensile strength of about 3,000 -p.s.i. and formed tough,clear, flexible, molded products. This copolymer also showed excellentlow temperature flexibility, as low as --87 C. Additionally, filmsprepared from this copolymer when extended, showed good recovery tooriginal dimensions when heated. Generally, the tensile strengths of thevinylcyclohexane block copolymersincreased as the amount ofvinylcyclohexane polymeric block sequences increased, and the yieldstrengths of the about 50 mole percent vinylcyclohexane structural unitsto about 82 mole percent vinylcyclohexane structural units weregenerally more rigid than the mixed block copolymers and possessedsomewhat higher heat distortion temperatures with slightly lower impactstrengths. The vinylcyclohexane block polymers prepared from theessentially complete hydrogenation of ternary styrene-butadienestyreneblock polymers had higher impact strengths than those polymers preparedfrom the hydrogenation of the binary styrene-butadiene polymers.-

In the aforementioned copolymers, i.e., those containing an excess of 50mole percent vinylcyclohexane structural units, the microstructure alsoinfluenced the physical and chemical properties of thecopolymer. As theethyl group content of the polyethylene block was increased, the impactstrength was increased and the tensile strengths and rigidity weredecreased.

' What is claimed is:

1. A rigid, optically clear, block copolymer having the generalconfiguration S-B comprising from about 10 percent by weight to about 95percent by weight hydrogenated polyvinyl aromatic blocks (S) andcorrespondingly from about 5 percent by weight to about 90 percent ,byweight hydrogenated conjugated polydiene blocks mixed block polymer asindicated by m.

block copolymers prepared via essentially complete hydrogenation of astyrene-butadieneblock polymer substrate containing a major portion of1,2 poly(butadiene) content, e.g. Run 95, had a' very lowtensile'strength (less than 100 psi.) though these copolymers formedhighly extensible andflexible films. The vinylcyclohexane-blockcopolymers prepared by the essentially complete hydrogenation ofisoprene-styrene block copolymers containing a majority of1,4-polyisoprene block sequences formed highly flexible, clear,reasonably tough moldings, however, their tensile strengths were lowerthan those of the polymers prepared from the essentially completehydrogenationofi polystyrene-1,4-polybutadiene block structures.

It will be noted from the examples that thosevinylcyclohexanealkyl-substituted polyethylene block copolymerscontaining in excess of about 50 mole percent vinylcyclohexanestructural units are rigid, clear thermoplastics exhibiting high heatdistortion temperatures and high tensile strengths. Also, those polymerscontaining,

in excess of about, 82 mole percent vinylcyclohexane structural unitsexhibit inferior physical properties. The pure block vinylcyclohexanepolymers containing from (B) wherein the unsaturation of the polymer isreduced by hydrogenation to a value of less than 3 percent residualaromatic unsaturation and wherein the block polymer is a 2. A blockpolymer having the general configuration S-B comprising from about toabout 5 percent by weight hydrogenated vinyl aromatic blocks (S) and correpondingly from about 10 percent to about percent by weighthydrogenated conjugated diene blocks (B) wherein the unsaturation of thepolymer is reduced by hydrogenation to a value of less than 3 percentresidual aromatic unsaturation and wherein the block polymer is a pureblock polymer. 1' 6 '3.,The block polymer of claim 1 wherein theconjugated diene blocks are polybutadiene and the vinyl aromatic blocksare polystyrene.

4. The block polymer of claim 2 wherein the conjugated diene blocks arepolybutadiene and the vvinyl aromatic blocks are polystyrene.

, References Cited UNITED STATES PATENTS 3,231,635 1/1966 Holden'et' al.2604,876XR' 3,242,038 3/1966 Dallas et al. 161-253 3,333,024 7/1967Haefele et a1. 260-880 2,864,809 12/1958 Jones et a]. 260--85.12,975,160 3/1961 Zelinski 260-837 3,239,478 3/1966 Harlan, Jr. 260-880XR3,431,323 13/1969 Jones 260880 FOREIGN PATENTS 621,955 6/1961 Canada26094.7H

JAMES A. SEIDLECK, Primary Examiner us. c1. X.R. 260880B UNITED STATESPATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,598 Dated August10, 1971 Inventor(s) Donald F Hoeg et 1 It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

Column 6, lines 20 to 24, "Grams M oofmerno" should read Grams ofMonomer Signed and sealed this 1st day of August 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents

